test(plugins): avoid subprocess in legacy plugin-sdk import test

src/plugins/loader.test.ts

@@ -1,8 +1,6 @@
-import { execFileSync } from "node:child_process";
 import fs from "node:fs";
 import os from "node:os";
 import path from "node:path";
-import { pathToFileURL } from "node:url";
 import { afterAll, afterEach, describe, expect, it, vi } from "vitest";
 import { withEnv } from "../test-utils/env.js";
 async function importFreshPluginTestModules() {
@@ -1354,37 +1352,25 @@ describe("loadOpenClawPlugins", () => {
 };`,
     });
 
-    const loaderModuleUrl = pathToFileURL(
-      path.join(process.cwd(), "src", "plugins", "loader.ts"),
-    ).href;
-    const script = `
-      import { loadOpenClawPlugins } from ${JSON.stringify(loaderModuleUrl)};
-      const registry = loadOpenClawPlugins({
-        cache: false,
-        workspaceDir: ${JSON.stringify(plugin.dir)},
-        config: {
-          plugins: {
-            load: { paths: [${JSON.stringify(plugin.file)}] },
-            allow: ["legacy-root-import"],
-          },
-        },
-      });
-      const record = registry.plugins.find((entry) => entry.id === "legacy-root-import");
-      if (!record || record.status !== "loaded") {
-        console.error(record?.error ?? "legacy-root-import missing");
-        process.exit(1);
-      }
-    `;
-
-    execFileSync(process.execPath, ["--import", "tsx", "--input-type=module", "-e", script], {
-      cwd: process.cwd(),
-      env: {
-        ...process.env,
+    const registry = withEnv(
+      {
         OPENCLAW_BUNDLED_PLUGINS_DIR: "/nonexistent/bundled/plugins",
       },
-      encoding: "utf-8",
-      stdio: "pipe",
-    });
+      () =>
+        loadOpenClawPlugins({
+          cache: false,
+          workspaceDir: plugin.dir,
+          config: {
+            plugins: {
+              load: { paths: [plugin.file] },
+              allow: ["legacy-root-import"],
+            },
+          },
+        }),
+    );
+
+    const record = registry.plugins.find((entry) => entry.id === "legacy-root-import");
+    expect(record?.status).toBe("loaded");
   });
 
   it("prefers dist plugin-sdk alias when loader runs from dist", () => {